It is the universal aim of valve designers to improve operating performance, reduce size relative to flow capacity, and to lower production costs.
In the past, valve bodies have been formed by extensive machining of solid material and more recently valve bodies have been die cast from metal or injection molded from plastic materials. Die casting has distinct advantages over machined valve bodies because of free holes and extra shaping which can be obtained. Even more sophisticated valve body configurations are possible through plastic molding.
However, die cast and molded valve bodies, as currently designed and produced, generally require substantial machining, port thread inserts, retaining caps, gaskets, and assembly screws. To form internal channels that intersect, expensive drilling and plugging operations are necessary. Further, grooves and large internal galleries are not normally formed in the molding process, because core pin removal would be impossible. Therefore, extra parts are required to form galleries and grooves which consume space and add to the overall cost of the valve.
Many valves include push-in fittings, in which the flow tubes can be inserted and removed from the valve body without the use of a tool. The normal push-in fitting consists of a threaded body, a collet to attach the body to the tube and an O-ring seal. The body of the fitting represents the major share of the cost and size of the fitting.
Exhaust silencing is also used with many pneumatic valves and this is accomplished by turning conically shaped sintered metal elements into the valve exhaust port. In most situations the valve silencing element is required to be installed by the valve user, which adds to the overall cost of the valve.